Shiro Gohda

The content and the oxidation state of arsenic and antimony in coastal water of Japan

The content and the oxidation state of arsenic and antimony in coastal seawater were determined coupled with chemical separation and neutron activation method. The contents of arsenic and antimony in coastal seawater were estimated to be 1.56–2.73Μg As/l, 0.25–0.57Μg Sb/l. Most parts of these elements exist as soluble ionic species, passing through 0.45Μ pore-size membrane filter, and at surface, 80–97% of arsenic occurs as arsenate and 70–94 % of antimony may occurs as antimonate. The vertical distribution of arsenite and arsenate is almost constant from the surface to 1,200 m depth. However the distribution of Sb(III) and Sb(V) is much more complicated with depth.

Chemical forms of chromium in natural water

The interaction of chromium (III) with humic substances obtained from pond sediment was experimentally studied using electrophoresis combined with ultrafiltration. The results show that within the neutral pH range chromium (III) in the presence of humic substances and some organic acids forms uncharged and/or negatively charged organic complexes of various molecular weights. A part of the chromium(III)-humic or -fulvic acid complexes having a negative charge was of lower molecular weight. Chromium (III) spiked in fresh water exists as various soluble anionic and/or uncharged species, and the molecular weights of these anionic complexes correspond to those of chromium(III)-humic and -fulvic complexes. These complexes may remain as stable dissolved forms for 10 days. The significance of the occurrence of chromium(III)-organic complexes in natural water in the geochemical cycle of chromium in the hydrosphere is discussed.

Studies on chlorophyll degradation process in sediments by high-performance liquid chromatography.

クロロフィルは生物活性の失活にともない,フェオフィチンを始めとする多種多様な分解物へと変化する。しかし,それらの構造はクロリン環を母核とする非常に類似したものであり,いまだその地球化学的.生物化学的挙動は明らかにされていない。本研究では,クロロフィルおよびその分解物の, 蛍光検知逆相高速液体クロマトグラフィーにおける挙動を検討し,それらの分離.同定.定量法を確立した。さらに本法を,堆積物中のクロロフィル類の分析に適用し,クロロフィル,フェオフィチン,フェオホルビド,メチルフェオホルビド,ピロフェオホルビドおよびピロフェオフィチンの存在を明らかにするとともに,堆積物中におけるクロロフィル続成分解過程の解明を試みた。

Determination of V in environmental reference materials by polarized Zeeman graphite furnace aas.

偏光ゼーマン黒鉛炉AASで環境試料中のVを迅速簡便,高精度に定量するための基礎的条件を検討した.粉末試料は炭酸ナトリウムで融解し,水を加えてVを温浸し,不溶性残留物を〓別した〓液を測定試料とした.チューブ型パイロ化黒鉛炉と光温度制御装置を併用することにより高感度,高精度なVの定量法を確立した.V濃度0.2ppmの2%炭酸ナトリウム溶液10mm3を炉に注入した場合の吸光度の相対標準偏差は2.1%であり,本法によるVの検出限界は0.06ngであった.本法を岩石,たい積物などの環境標準物質中のVの定量に応用し,迅速に精度良く定量できた.